Die for slotting and shaping bicycle truss tube ends



Feb. 3, 194. F. w. SCHWINN 29435394? DIE FOR SL OTTING AND SHAPING BICYCLE TRUSS TUBE ENDS 2 sheets-sheet 1 Original Filed Nov. 19, 1943 ffvmmew Feb. 3, 1948. F. w. SCHWINN 4 DIE FOR SLOTTING AND SHAPING BICYCLE TRUSS TUBE ENDS Original Filed Nov. l9, 1945 2 Sheets-Sheet 2 Patented Feb. 3, 1948 UNITED om ron SLOTTING ANnsnArI-Ne excrete muss TUBE ENDS Frank Schwinn", Chiago,'lll.

Original application November 19,1943, Serial No. 510,876. Divided andhthis application May 3, 1945, Serial No. 591,798

2 Claims; 1

The present invention relates to truss brackets for securing the truss tubes which are used on a bicycle for reenforcing thefront fork.

This application is a. division of prior applica-. tion, Serial No. 510,876, filed November 19, 1943, now matured into Patent No. 2,384,968, issued September 18, 1945, for Truss bracket.

One of the objects of the invention is the provision of an improved bracket for securing the truss tubes that reenforce the front fork of a bicycle, to the steering column tube, in'which the truss tubes are more securely mounted than in the devices of the prior art and which, is adapted to be manufactured with less expense than those devices.

Another object of the invention is the provision of an improved bicycle front fork truss construction, particularly at the upper end thereof, by means of whichamore durable andsturdy structure is provided and by means of which the truss tubes and bracket are adapted to be secured together rigidly with a single screw bolt.

Another object of the invention is the provision of an improved trusstube bracket structure which is simple, sturdy, capable of economical manufacture, and which lends itself to manufacture by stamping or punching operations so as to reduce to a minimum the machine operations. which are usually necessary in making such device.

Another object of the invention is the provision of an improved method f making truss tubes for use with the improved bracket and improved tools to be used in the making of the truss tubes embodying the invention. a

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings in which similar characters ofreference indicate similar parts throughout the several views.

Referring to the drawings, of which there are two sheets,

Figure 1 is a fragmentary side elevational view of a bicycle construction at the steering post tube and truss, embodying the invention;

Fig. 2 is a fragmentary front elevational view of the same structure;

Fig. 3 is a transverse sectional View taken on the plane of the line 33 of Fig. 1 looking inthe direction of the arrows;

Fig. 4 is a similar sectional view taken on the plane of the line l4 of Fig. 1 looking in the direction of the arrows;

Fig. 5 is a view in perspective, taken from the top and front of the truss tube bracket, showing the mode of securem ent of the truss tubes and the truss brackets, it is. necessary to describe the structure of the truss brackets which are to be m de- Referring to Fig. 1, I0 indicates. in its entirety the bicycle frame, of which only such parts are shown as cooperate, with the new truss tube bracketthat forms the subject of the present invention. This tru'sstube bracket is usually secured between the head adjusting cup II and lock nut l-Z- on the steering column tube 53- of a bicycle. g

The truss tube bracket is shown in connection with a pair of truss tubes M, ii, the upper ends of which are secured to the head adjusting cup by means of the bracket i6; The head adjusting cup is preferably provided with an upwardlyextending tubular portionv ll of reduceddiarneter and the bracket 1'6 is preferably provided with a ircular bore 18 adapted to pass this portion of reduced size of the head adjusting cup.

Surrounding the bore I 8 the bracket I6 may be circular but it is provided with, a forwardly and downwardly extending securing fiangeiQ that is adapted to be secured to the truss rods l4 and i5. The annular portion of the bracket H5 is pref:- erably provided with a depending border flange 20 which isannula-rexcept for the fact that in front wherethe securing 'fiange as is provided on the bracket the'border flange 2% extends down the sides of this securing flange l9. Y

The border flange 20- is gradually increased in width at 2-! and gradually curved until at its lower end the securingflan'ge i9 is provided with the oppositely located partially cylindrical tube em? bracing fianges 2'2, 2'3 'whichfor-"mfintegralf extegsions of the border flange 20 at its wider portion 2|.

. The cylindrical tube embracing flanges 22,23 have their innercylindrical surfaces 24 25 shaped o fit o he id of. t e c i dric l e d; non tions'. 26;, 21; of, the truss tubes I4 and i5 so that the truss ubes fit snugly in.v these. embracing 3 flanges over a portion of the periphery of the truss tubes which is preferably substantially half of the periphery or slightly more than half.

The edges 28, 29 of these tube embracing flanges 22, 23 are located on the under side of the bracket and are spaced from each other by a distance which is sufiicient to permit either one of the tubes to be inserted inside the bracket when the bracket is empty or when one tube is already in it, so that the tubes may be inserted from the bottom of the bracket and need not be inserted endwise. This is important because on certain types of bicycles it is not always possible to insert the tubes endwise into the cavity of the truss tube bracket although with the particular construction shown that can also be done when the lower end of each truss tube is entirely free.

The securing flange l9 of the truss bracket is is formed with a centrally located through bore 39 adapted to pass the shank 3| of the screw bolt 32 and the bracket is also preferably formed with a downwardly turned intermediate pressed rib 33 below or outwardly of the bolt 32, this rib coming between the two truss rods I4 and i as they emerge from the bracket.

The bolt 32 has its shank 3| provided with a threaded portion 34 and the bolt has a non-circular head 35 for use in turning the bolt in threaded engagement with a wedging member 36. The wedging member 36 comprises a metal mei ber of suflicient length to project beyond the bolt 32 a substantial distance above and below the bolt and of suflicient width at its widest portion to be received between the edges 28, 29 of the tube embracing flanges 22, 23.

The wedging member 35 has a threaded through bore 31 for receiving the threaded portion 34 of bolt 32. Its cross-sectional shape is shown in Fig. 3 and it may have an outer convex surface 38 but is provided with a pair of partially cylindrical wedging surfaces 39, 49 for engaging each of the tubes l4 and I 5. The inner edge 4| may be plane or curved and the two lateral edges 42, 43 may be plane.

The truss tubes 14 and I5 are shown in section in Fig. 6 and these tubes are formed at their upper ends with an outward bend at 44 so that the extreme upper end portions 45, 46 may extend substantially parallel to each other while the lower portions 41, 48 may diverge after they emerge from the bracket 16. It will be understood that the two truss tubes l4 and i5 diverge from each other in order that they may be secured to the front fork at each of its sides.

In order firmly to secure the parallel portions 45, 46 of the truss tubes in the bracket it, each truss tube is preferably provided on that side of the tube which is adjacent the bolt 32 with a partially cylindrical groove 49 or 50, the groove being complementary in size and shape to that portion of the bolt shank 3| which each truss rod engages. This groove 49 is preferably formed by a pressing or punching operation and during the formation of such a groove there is an excess of metal at the wall of the groove 49 in the truss tube and this excess of metal must be disposed of in'some way. According to the method by means of which I prefer to form the truss tube, the excess metal is punched out to form an aperture at 5| in the middle of the wall of the groove 45.

The partially cylindrical groove 49 may have its wall portions indicated. toward the top of the bolt by the numeral 52, and its wall portion toward the bottom of the bolt by the numeral 53. It will thus be observed that the bolt 32 engages those portions 53 of the groove 49 to prevent the truss tubes from being pulled downwardly and the bolt 32 engages those portions 52 of the groove 49 or 59 to prevent the truss tubes from being moved upwardly in the bracket. The bolt is of course held in place in the bracket by its engagement in the bore 39.

In addition to the foregoing shoulders for holding the truss tubes, the wedging member 39 is engaged by the threaded portion 34 of the bolt 32 and drawn into snugly fitting engagement with each truss tube, causing the truss tubes to spread into their proper position engaging the cylindrical surfaces 24, 25 of the tube embracing flanges 22, 23. It should be understood, however, that all of these parts fit quite snugly so that the wedging member 36 merely serves to hold them all in snug engagement with each other, that is, it causes the tubes to have tight engagement with the bracket and the tubes to have tight engagement with the bolt and the wedging member.

Referring to Fig. '7, this is an exploded view of the punch and die which may be used to form the tube which is shown between them. The die 54 may consist of a block of metal such as steel which has a plane stable base 55, the width of which is augmented by the laterally projecting flanges 56, 51. The body of the die may consist of a portion 58 which projects upwardly from the base 55 and is formed with a centrally and longitudinally extending groove 59 of sufficient width to receive a truss tube I4 or IS.

The groove 59 is bounded by the two upwardly extending flange portions 59, 6| and the base of the groove 59 may be substantially half cylindrical as indicated at 62 except that the cylindrical groove portion 62 has two parts which are joined at33 and which are at an angle to each other, that is, the part 34 extends diagonally upward in the groove 59 and the part 65 extends horizontally. This is for the purpose of bending the truss tube M or 5 at the point 44 and forming the parallel end portions 45, 46 on the truss tubes.

At its leftrend the die preferably includes a stop in the form of a block 66 of metal which is welded or otherwise secured to the body 58 and the block 36 preferably has a short mandrel 67 comprising a short section of rod of cylindrical shape adapted to fit in the end of the truss tube rod to center the truss tube rod and to prevent its being forced out of round at its extreme end portion.

Mandrel 6? may have its inner end formed with a curved partially cylindrical surface 68 corresponding to the under side of the wall portion 52 of groove 49 in the truss rod i4. Of course the mandrel 6'! is spaced from the walls of the groove 59 and from the base 65 of the groove sufficiently to permit the truss tube to be inserted around the mandrel 61.

The punch which is indicated in its entirety by the numeral 79 is likewise preferably provided with a wider base portion 1| having a depending body portion 12 the sides i3, 14 of which are parallel and adapted to be slidably received in the groove 59 of the die. The body portion 12 conforms generally to the surfaces of the die 54 when 7 the die has a truss tube l4 as illustrated in Fig. 7

in the groove 59. This means that, generally speaking, there is a partially cylindrical groove 15 extending all the way along the lower edge of the body 12 for engaging the truss tube l4 in the die 54 except that there is an intermediate transverse cylindrical portion 15 on the lower surface of the punch 70 for forming the cylindrical groove 49 in the truss tube [4.

Due to the necessity for disposing of the excess metal of the truss tube that comes into existence when the wall is pressed downwardly to form the cylindrical groove 49, it is also necessary to provide a depending centrally located longitudinally extending rib l! on the lower surface of the die at this point for forming the slot 5|. Thus the die at this point has cylindrical surfaces on each side of the projecting rib TI and these cylindrical surfaces are indicated again at 16 (Fig. 8).

As the tubes themselves'are easily sheared, the rib 11 will punch out a slot at 5| to dispose of the excess metal and when the straight truss tube blank is placed in the die and acted upon by the punch, the truss tube will be simultaneously bent and pressed into the desired shape shown in Fig. 7. Thus it is unnecessary to thread the end of the truss tube as in the devices of the prior art. Yet the truss tube is provided with retaining shoulders having a much greater area of engagement with I the single securing bolt that holds the wedging at this groove is punched out and upon separating the punch and die the tube is ready for use.

The operation of the truss tube bracket is as follows: The bolt and wedging member having been removed, the bracket may be secured on the head adjusting cup or it may be assembled with the truss tubes apart from the cup. In either event the end portions 45, 4B of the truss tubes are placed in the bracket and the bolt is inserted through the bore in the bracket and through the grooves 49, 56 of the truss tubes. The wedging member is then placed in engagement with the bottom of the truss tubes and the bolt is rotated to draw the wedging member inwardly until it engages the tubes tightly and they engage the bolt and bracket tightly. All of these parts should fit snugly and thus the tubes are firmly secured against longtiudinal or lateral movement and they are adapted to resist the tension or compression forces that are exerted on the truss tubes to draw them out of or force them into the bracket.

It will thus be observed that I have invented an improved truss tube bracket by means of which the truss tubes may be more securely mounted in the bracket than with any of the devices of the prior art with which I am familiar. A single bolt and wedging member serving as a nut not only draws the truss tubes into the bracket but it secures them against longitudinal movement in either direction. The present bracket and tube construction involves only a few stamping operations since the bracket itself may be formed by punching or stamping and the tubes are simultaneously given all of their formations by one operation of a punch and die.

The present construction may be made at a minimum cost and may thus be placed within reach of a large number of purchasers. The construction is simple and sturdy and adapted to be used for a long period of time without necessity for repair or replacement.

The truss tubes are thus adapted to resist the forces which tend to break or bend the front fork more strongly than the devices of the prior art '6 and a very light yet rigid construction is provided for the front fork.

While I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the claims.

Having thus described m invention, what I claim as new and desire to secure by Letters Patent of the United States, is:

1. A die assembly for making truss tubes comprising, in combination, a female die member having a groove of a size and shape to fit and provide support for substantially half of the periphery of a tube, said female die also having at one end of said groove a mandrel carried by the female die and of a shape and size to fit into and support the end of said tube. the inner end of said mandrel having a partially cylindrical concave surface with the axis of the cylindrical surface transverse to the axis of the groove, and a male die member having a base portion and a projecting flange portion of a size to fit and be received by said groove in the female die, said flange portion having thereon near one end a partially cylindrical formation extending transversely of the longitudinal axis of the flange portion and projecting outwardly from a longitudinally extending arcuate groove in the tube-engaging end of said flange portion, whereby engagement of said dies with the tube provides the tube with a transverse groove adjacent one end, said flange portion of the male die also having thereon a cutting member extending longitudinally of the flange portion and projecting therefrom to cut a slot in the wall of the tube at said transverse groove prior to and during the formation of the transverse groove,

2. A die assembly for forming truss tubes from substantially cylindrical tube stock and comprising, in combination, a female die member having therein a partially cylindrical groove of a size to fit and provide support for a substantial portion of the tube periphery, said female die also having thereon at one end of the groove a mandrel of a shape and size to fit into and support the end portion of the tube, the inner end of said mandrel having a partially cylindrical concave surface with the axis of the cylindrical surface transverse to the longitudinal axis of said groove, and a male die member including a projecting flange portion of a size to fit and be received by said groove in the female die, said flange portion having thereon near the end thereof which fits into the end of the groove wherein said mandrel is located a partially cylindrical formation extending transversely of the longitudinal axis of the flange portion and projecting outwardly from a longitudinally extending arcuate groove in the tube-engaging end of the flange portion, whereby the forced engagement of the dies with the tube provides the tube with a transverse groove adjacent one end, said flange portion of the male die also having thereon a cutting member extending longitudinally of the flange portion and projecting therefrom to cut a slot in the wall of the tube at said transverse groove prior to and during the formation of the transverse groove, and said flange portion and groove of the male and female dies respectively being shaped to form an obtuse angle bend near said transverse groove in the tube during the formation of the transverse groove.

FRANK W. SCHWINN.

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